If you’ve ever stepped off the bike during a triathlon and wondered why your legs suddenly feel like they’re made of concrete, you’re not alone.
It isn’t because you’ve forgotten how to run.
It’s because your body is adapting from one movement pattern to another, often after an hour or more of cycling. That awkward feeling is one of the biggest challenges in triathlon, and it’s exactly why brick sessions are such an important part of your training.
What Is a Brick Session?
A brick session simply combines two disciplines back-to-back, most commonly a bike followed immediately by a run.
The name is thought to come from the feeling many athletes experience when they first start running—as though they’ve got bricks attached to their feet!
While brick sessions also help you practise race-day logistics, their biggest benefit is teaching your body how to transition efficiently from cycling to running.
Why Your Legs Feel So Strange
Cycling and running use many of the same muscles, but they recruit them in different ways.
During the bike leg your cadence, muscle firing patterns and posture are completely different to running. When you suddenly ask those same muscles to switch roles, your brain needs a few minutes to recalibrate.
That’s why the first kilometre often feels awkward, heavy and uncoordinated.
The good news?
With regular brick training, your body becomes much better at making that transition.
Brick Sessions Train Your Nervous System
Many athletes assume brick sessions are about building fitness.
They’re actually more about building familiarity.
Every time you complete a bike-to-run brick, you’re teaching your nervous system to make the change more smoothly. Over time you’ll notice:
- Your running form settles more quickly.
- Your stride feels more natural.
- Your cadence returns faster.
- Your confidence grows on race day.
The strange feeling never disappears completely, but it becomes far less intimidating.
You Don’t Need Massive Brick Sessions
One of the biggest mistakes triathletes make is thinking every brick needs to be long and exhausting.
It doesn’t.
A simple session such as:
- 45–60 minutes riding
- Immediately followed by a 10–20 minute easy run
can provide all the adaptation you’re looking for.
The goal isn’t to set a running PB.
The goal is simply to practise running well after riding.
Focus on Good Running Form
During the run portion of a brick session, concentrate on:
- Running tall.
- Taking quick, light steps.
- Relaxing your shoulders.
- Letting your legs gradually find their rhythm.
Avoid sprinting straight out of transition. Give your body a few minutes to adapt before worrying about pace.
Practise Like You Race
Brick sessions are also the perfect opportunity to rehearse your race-day routine.
Use them to practise:
- Changing shoes quickly.
- Putting on your race belt.
- Running with your nutrition.
- Starting at your planned race pace.
Every practice session builds confidence, and confident athletes generally race better.
Final Thoughts
Brick sessions aren’t designed to leave you exhausted—they’re designed to make race day feel familiar.
The more often you practise running immediately after cycling, the less intimidating that transition becomes. Instead of spending the first kilometre wondering what’s happened to your legs, you’ll settle into your rhythm sooner, run more efficiently, and finish stronger.
Like many aspects of triathlon, it’s not about doing one huge session. It’s about repeating the right training often enough that your body knows exactly what to do when race day arrives.
Ready to Build Your Best Triathlon?
Whether you’re training for your first sprint triathlon, stepping up to an Olympic distance event, or preparing for an Ironman 70.3, I’d love to help.
Book a free, no-obligation 40-minute coaching call and we’ll discuss your goals, your current training, and the best path to achieving your next personal best.
There’s no pressure and no hard sell—just an opportunity to talk triathlon and see how I can help you train smarter and race with confidence.